A yearlong summer? That’s the secret scientists are using bringing endangered pond turtles back to the Northwest. (Think of all the other folks it would bring if we had summertime weather year-round. Hello, California!)
The Oregon Zoo has simulated 11 months of summertime warmth for nine western pond turtles to help them grow big faster so they can evade non-native bull frog predators and large-mouth bass. Tomorrow, the zoo and several partners will release the endangered reptiles into the wild of the Columbia Gorge.
Here’s how a simulated summer helps the species survive, from an Oregon Zoo news release (more on the program in this Oregon Field Guide video):
“The turtles think it’s summer year-round, so they never go into hibernation,” said Dr. David Shepherdson, Oregon Zoo conservation scientist. “They get bigger and bigger, experiencing almost three years’ growth in 11 months.”
Once the turtles reach a suitable size of about 70 grams (a little more than 2 ounces), they are returned to their homes and monitored for safety.
“Since the turtles are larger, predators such as non-native bullfrogs and large-mouth bass are no longer threats,” Shepherdson said.
The turtle reintroduction is part of a collaborative effort by the Oregon Zoo, Woodland Park Zoo, Washington Department of Fish and Wildlife, U.S. Fish and Wildlife Service and Bonneville Power Administration. As part of the Western Pond Turtle Recovery Plan, conservation scientists “head-start” newly hatched turtles gathered from wild sites, nurturing them at both zoos for about 11 months. Scientists estimate that 95 percent of the turtles released back to sites in the Columbia Gorge have survived.
This year marks the 20th anniversary of the Western Pond Turtle Recovery Plan, begun by the Woodland Park Zoo and WDFW in 1991. The Oregon Zoo has been a collaborator in the project since 2000.
“Spending the first months of their life at the zoo gives the turtles a real edge,” explained Shepherdson. “We’re glad we could provide assistance in helping save these highly endangered turtles.”
Local youths enrolled in the Jane Goodall Environmental Middle School and the Skamania County Forest Youth Success Program, plus teens from the U.S. Fish and Wildlife Service’s Youth Conservation Corps and the Oregon Zoo’s Zoo Animal Presenters program, will help biologists release the turtles in the Columbia River Gorge.
“It is one thing to learn about conservation efforts, but it makes a much bigger impact when you actually see a zoo-reared turtle released back into the wilds of the Columbia Gorge,” Shepherdson said.
Two decades ago, western pond turtles were on the verge of completely dying out in Washington, with only 150 turtles left in the Columbia River Gorge. Today, researchers estimate that there are more than 1,500. Habitat degradation and disease were, and still are, problems, but the biggest threat to fragile baby turtles is the bullfrog. Native to areas east of the Rockies, this nonindigenous frog has thrived throughout the West, driving pond turtles and a host of other small, vulnerable aquatic species to the brink of extinction.
To help restore these rare pond turtles to their natural habitat, recovery workers take to the field each year. Under the supervision of western pond turtle experts Kate and Frank Slavens, they count, trap and fit transmitters on adult female western pond turtles. The female turtles are monitored every two hours during the nesting season to determine where they nest. The nests, which the females dig in the ground and then cover after depositing their eggs, are protected with wire “exclosure” cages that help prevent predators from eating the eggs. The eggs are then allowed to incubate naturally, and the hatchlings are collected in the fall. The hatchlings are about the size of a quarter when they are removed and taken to the zoo facilities, where they can grow in safety. Unlike wild turtles, zoo turtles are fed throughout the winter, so by their summer release, the 11-month-olds are about as big as 3-year-old turtles that grew up in the wild.
Now listed as an endangered species in Washington and a sensitive species in Oregon, the western pond turtle was once common from Baja California to the Puget Sound. The Oregon Zoo’s participation in the Western Pond Turtle Recovery Plan is funded through The Oregon Zoo Foundation’s Future for Wildlife conservation fund, the Bonneville Power Administration and the Washington Department of Fish and Wildlife.